InstCombineCalls.cpp revision 78f8ef42173a3a9867ed789073d4ddc652fb7ff2 
1//===- InstCombineCalls.cpp -----------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the visitCall and visitInvoke functions.
11//
12//===----------------------------------------------------------------------===//
13
14#include "InstCombine.h"
15#include "llvm/Support/CallSite.h"
16#include "llvm/Target/TargetData.h"
17#include "llvm/Analysis/MemoryBuiltins.h"
18#include "llvm/Transforms/Utils/BuildLibCalls.h"
19#include "llvm/Transforms/Utils/Local.h"
20using namespace llvm;
21
22/// getPromotedType - Return the specified type promoted as it would be to pass
23/// though a va_arg area.
24static Type *getPromotedType(Type *Ty) {
25  if (IntegerType* ITy = dyn_cast<IntegerType>(Ty)) {
26    if (ITy->getBitWidth() < 32)
27      return Type::getInt32Ty(Ty->getContext());
28  }
29  return Ty;
30}
31
32
33Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
34  unsigned DstAlign = getKnownAlignment(MI->getArgOperand(0), TD);
35  unsigned SrcAlign = getKnownAlignment(MI->getArgOperand(1), TD);
36  unsigned MinAlign = std::min(DstAlign, SrcAlign);
37  unsigned CopyAlign = MI->getAlignment();
38
39  if (CopyAlign < MinAlign) {
40    MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
41                                             MinAlign, false));
42    return MI;
43  }
44
45  // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
46  // load/store.
47  ConstantInt *MemOpLength = dyn_cast<ConstantInt>(MI->getArgOperand(2));
48  if (MemOpLength == 0) return 0;
49
50  // Source and destination pointer types are always "i8*" for intrinsic.  See
51  // if the size is something we can handle with a single primitive load/store.
52  // A single load+store correctly handles overlapping memory in the memmove
53  // case.
54  unsigned Size = MemOpLength->getZExtValue();
55  if (Size == 0) return MI;  // Delete this mem transfer.
56
57  if (Size > 8 || (Size&(Size-1)))
58    return 0;  // If not 1/2/4/8 bytes, exit.
59
60  // Use an integer load+store unless we can find something better.
61  unsigned SrcAddrSp =
62    cast<PointerType>(MI->getArgOperand(1)->getType())->getAddressSpace();
63  unsigned DstAddrSp =
64    cast<PointerType>(MI->getArgOperand(0)->getType())->getAddressSpace();
65
66  IntegerType* IntType = IntegerType::get(MI->getContext(), Size<<3);
67  Type *NewSrcPtrTy = PointerType::get(IntType, SrcAddrSp);
68  Type *NewDstPtrTy = PointerType::get(IntType, DstAddrSp);
69
70  // Memcpy forces the use of i8* for the source and destination.  That means
71  // that if you're using memcpy to move one double around, you'll get a cast
72  // from double* to i8*.  We'd much rather use a double load+store rather than
73  // an i64 load+store, here because this improves the odds that the source or
74  // dest address will be promotable.  See if we can find a better type than the
75  // integer datatype.
76  Value *StrippedDest = MI->getArgOperand(0)->stripPointerCasts();
77  if (StrippedDest != MI->getArgOperand(0)) {
78    Type *SrcETy = cast<PointerType>(StrippedDest->getType())
79                                    ->getElementType();
80    if (TD && SrcETy->isSized() && TD->getTypeStoreSize(SrcETy) == Size) {
81      // The SrcETy might be something like {{{double}}} or [1 x double].  Rip
82      // down through these levels if so.
83      while (!SrcETy->isSingleValueType()) {
84        if (StructType *STy = dyn_cast<StructType>(SrcETy)) {
85          if (STy->getNumElements() == 1)
86            SrcETy = STy->getElementType(0);
87          else
88            break;
89        } else if (ArrayType *ATy = dyn_cast<ArrayType>(SrcETy)) {
90          if (ATy->getNumElements() == 1)
91            SrcETy = ATy->getElementType();
92          else
93            break;
94        } else
95          break;
96      }
97
98      if (SrcETy->isSingleValueType()) {
99        NewSrcPtrTy = PointerType::get(SrcETy, SrcAddrSp);
100        NewDstPtrTy = PointerType::get(SrcETy, DstAddrSp);
101      }
102    }
103  }
104
105
106  // If the memcpy/memmove provides better alignment info than we can
107  // infer, use it.
108  SrcAlign = std::max(SrcAlign, CopyAlign);
109  DstAlign = std::max(DstAlign, CopyAlign);
110
111  Value *Src = Builder->CreateBitCast(MI->getArgOperand(1), NewSrcPtrTy);
112  Value *Dest = Builder->CreateBitCast(MI->getArgOperand(0), NewDstPtrTy);
113  LoadInst *L = Builder->CreateLoad(Src, MI->isVolatile());
114  L->setAlignment(SrcAlign);
115  StoreInst *S = Builder->CreateStore(L, Dest, MI->isVolatile());
116  S->setAlignment(DstAlign);
117
118  // Set the size of the copy to 0, it will be deleted on the next iteration.
119  MI->setArgOperand(2, Constant::getNullValue(MemOpLength->getType()));
120  return MI;
121}
122
123Instruction *InstCombiner::SimplifyMemSet(MemSetInst *MI) {
124  unsigned Alignment = getKnownAlignment(MI->getDest(), TD);
125  if (MI->getAlignment() < Alignment) {
126    MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
127                                             Alignment, false));
128    return MI;
129  }
130
131  // Extract the length and alignment and fill if they are constant.
132  ConstantInt *LenC = dyn_cast<ConstantInt>(MI->getLength());
133  ConstantInt *FillC = dyn_cast<ConstantInt>(MI->getValue());
134  if (!LenC || !FillC || !FillC->getType()->isIntegerTy(8))
135    return 0;
136  uint64_t Len = LenC->getZExtValue();
137  Alignment = MI->getAlignment();
138
139  // If the length is zero, this is a no-op
140  if (Len == 0) return MI; // memset(d,c,0,a) -> noop
141
142  // memset(s,c,n) -> store s, c (for n=1,2,4,8)
143  if (Len <= 8 && isPowerOf2_32((uint32_t)Len)) {
144    Type *ITy = IntegerType::get(MI->getContext(), Len*8);  // n=1 -> i8.
145
146    Value *Dest = MI->getDest();
147    unsigned DstAddrSp = cast<PointerType>(Dest->getType())->getAddressSpace();
148    Type *NewDstPtrTy = PointerType::get(ITy, DstAddrSp);
149    Dest = Builder->CreateBitCast(Dest, NewDstPtrTy);
150
151    // Alignment 0 is identity for alignment 1 for memset, but not store.
152    if (Alignment == 0) Alignment = 1;
153
154    // Extract the fill value and store.
155    uint64_t Fill = FillC->getZExtValue()*0x0101010101010101ULL;
156    StoreInst *S = Builder->CreateStore(ConstantInt::get(ITy, Fill), Dest,
157                                        MI->isVolatile());
158    S->setAlignment(Alignment);
159
160    // Set the size of the copy to 0, it will be deleted on the next iteration.
161    MI->setLength(Constant::getNullValue(LenC->getType()));
162    return MI;
163  }
164
165  return 0;
166}
167
168/// visitCallInst - CallInst simplification.  This mostly only handles folding
169/// of intrinsic instructions.  For normal calls, it allows visitCallSite to do
170/// the heavy lifting.
171///
172Instruction *InstCombiner::visitCallInst(CallInst &CI) {
173  if (isFreeCall(&CI))
174    return visitFree(CI);
175
176  // If the caller function is nounwind, mark the call as nounwind, even if the
177  // callee isn't.
178  if (CI.getParent()->getParent()->doesNotThrow() &&
179      !CI.doesNotThrow()) {
180    CI.setDoesNotThrow();
181    return &CI;
182  }
183
184  IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
185  if (!II) return visitCallSite(&CI);
186
187  // Intrinsics cannot occur in an invoke, so handle them here instead of in
188  // visitCallSite.
189  if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
190    bool Changed = false;
191
192    // memmove/cpy/set of zero bytes is a noop.
193    if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
194      if (NumBytes->isNullValue())
195        return EraseInstFromFunction(CI);
196
197      if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
198        if (CI->getZExtValue() == 1) {
199          // Replace the instruction with just byte operations.  We would
200          // transform other cases to loads/stores, but we don't know if
201          // alignment is sufficient.
202        }
203    }
204
205    // No other transformations apply to volatile transfers.
206    if (MI->isVolatile())
207      return 0;
208
209    // If we have a memmove and the source operation is a constant global,
210    // then the source and dest pointers can't alias, so we can change this
211    // into a call to memcpy.
212    if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI)) {
213      if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
214        if (GVSrc->isConstant()) {
215          Module *M = CI.getParent()->getParent()->getParent();
216          Intrinsic::ID MemCpyID = Intrinsic::memcpy;
217          Type *Tys[3] = { CI.getArgOperand(0)->getType(),
218                           CI.getArgOperand(1)->getType(),
219                           CI.getArgOperand(2)->getType() };
220          CI.setCalledFunction(Intrinsic::getDeclaration(M, MemCpyID, Tys));
221          Changed = true;
222        }
223    }
224
225    if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
226      // memmove(x,x,size) -> noop.
227      if (MTI->getSource() == MTI->getDest())
228        return EraseInstFromFunction(CI);
229    }
230
231    // If we can determine a pointer alignment that is bigger than currently
232    // set, update the alignment.
233    if (isa<MemTransferInst>(MI)) {
234      if (Instruction *I = SimplifyMemTransfer(MI))
235        return I;
236    } else if (MemSetInst *MSI = dyn_cast<MemSetInst>(MI)) {
237      if (Instruction *I = SimplifyMemSet(MSI))
238        return I;
239    }
240
241    if (Changed) return II;
242  }
243
244  switch (II->getIntrinsicID()) {
245  default: break;
246  case Intrinsic::objectsize: {
247    uint64_t Size;
248    if (getObjectSize(II->getArgOperand(0), Size, TD))
249      return ReplaceInstUsesWith(CI, ConstantInt::get(CI.getType(), Size));
250    return 0;
251  }
252  case Intrinsic::bswap:
253    // bswap(bswap(x)) -> x
254    if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(II->getArgOperand(0)))
255      if (Operand->getIntrinsicID() == Intrinsic::bswap)
256        return ReplaceInstUsesWith(CI, Operand->getArgOperand(0));
257
258    // bswap(trunc(bswap(x))) -> trunc(lshr(x, c))
259    if (TruncInst *TI = dyn_cast<TruncInst>(II->getArgOperand(0))) {
260      if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(TI->getOperand(0)))
261        if (Operand->getIntrinsicID() == Intrinsic::bswap) {
262          unsigned C = Operand->getType()->getPrimitiveSizeInBits() -
263                       TI->getType()->getPrimitiveSizeInBits();
264          Value *CV = ConstantInt::get(Operand->getType(), C);
265          Value *V = Builder->CreateLShr(Operand->getArgOperand(0), CV);
266          return new TruncInst(V, TI->getType());
267        }
268    }
269
270    break;
271  case Intrinsic::powi:
272    if (ConstantInt *Power = dyn_cast<ConstantInt>(II->getArgOperand(1))) {
273      // powi(x, 0) -> 1.0
274      if (Power->isZero())
275        return ReplaceInstUsesWith(CI, ConstantFP::get(CI.getType(), 1.0));
276      // powi(x, 1) -> x
277      if (Power->isOne())
278        return ReplaceInstUsesWith(CI, II->getArgOperand(0));
279      // powi(x, -1) -> 1/x
280      if (Power->isAllOnesValue())
281        return BinaryOperator::CreateFDiv(ConstantFP::get(CI.getType(), 1.0),
282                                          II->getArgOperand(0));
283    }
284    break;
285  case Intrinsic::cttz: {
286    // If all bits below the first known one are known zero,
287    // this value is constant.
288    IntegerType *IT = dyn_cast<IntegerType>(II->getArgOperand(0)->getType());
289    // FIXME: Try to simplify vectors of integers.
290    if (!IT) break;
291    uint32_t BitWidth = IT->getBitWidth();
292    APInt KnownZero(BitWidth, 0);
293    APInt KnownOne(BitWidth, 0);
294    ComputeMaskedBits(II->getArgOperand(0), KnownZero, KnownOne);
295    unsigned TrailingZeros = KnownOne.countTrailingZeros();
296    APInt Mask(APInt::getLowBitsSet(BitWidth, TrailingZeros));
297    if ((Mask & KnownZero) == Mask)
298      return ReplaceInstUsesWith(CI, ConstantInt::get(IT,
299                                 APInt(BitWidth, TrailingZeros)));
300
301    }
302    break;
303  case Intrinsic::ctlz: {
304    // If all bits above the first known one are known zero,
305    // this value is constant.
306    IntegerType *IT = dyn_cast<IntegerType>(II->getArgOperand(0)->getType());
307    // FIXME: Try to simplify vectors of integers.
308    if (!IT) break;
309    uint32_t BitWidth = IT->getBitWidth();
310    APInt KnownZero(BitWidth, 0);
311    APInt KnownOne(BitWidth, 0);
312    ComputeMaskedBits(II->getArgOperand(0), KnownZero, KnownOne);
313    unsigned LeadingZeros = KnownOne.countLeadingZeros();
314    APInt Mask(APInt::getHighBitsSet(BitWidth, LeadingZeros));
315    if ((Mask & KnownZero) == Mask)
316      return ReplaceInstUsesWith(CI, ConstantInt::get(IT,
317                                 APInt(BitWidth, LeadingZeros)));
318
319    }
320    break;
321  case Intrinsic::uadd_with_overflow: {
322    Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
323    IntegerType *IT = cast<IntegerType>(II->getArgOperand(0)->getType());
324    uint32_t BitWidth = IT->getBitWidth();
325    APInt LHSKnownZero(BitWidth, 0);
326    APInt LHSKnownOne(BitWidth, 0);
327    ComputeMaskedBits(LHS, LHSKnownZero, LHSKnownOne);
328    bool LHSKnownNegative = LHSKnownOne[BitWidth - 1];
329    bool LHSKnownPositive = LHSKnownZero[BitWidth - 1];
330
331    if (LHSKnownNegative || LHSKnownPositive) {
332      APInt RHSKnownZero(BitWidth, 0);
333      APInt RHSKnownOne(BitWidth, 0);
334      ComputeMaskedBits(RHS, RHSKnownZero, RHSKnownOne);
335      bool RHSKnownNegative = RHSKnownOne[BitWidth - 1];
336      bool RHSKnownPositive = RHSKnownZero[BitWidth - 1];
337      if (LHSKnownNegative && RHSKnownNegative) {
338        // The sign bit is set in both cases: this MUST overflow.
339        // Create a simple add instruction, and insert it into the struct.
340        Value *Add = Builder->CreateAdd(LHS, RHS);
341        Add->takeName(&CI);
342        Constant *V[] = {
343          UndefValue::get(LHS->getType()),
344          ConstantInt::getTrue(II->getContext())
345        };
346        StructType *ST = cast<StructType>(II->getType());
347        Constant *Struct = ConstantStruct::get(ST, V);
348        return InsertValueInst::Create(Struct, Add, 0);
349      }
350
351      if (LHSKnownPositive && RHSKnownPositive) {
352        // The sign bit is clear in both cases: this CANNOT overflow.
353        // Create a simple add instruction, and insert it into the struct.
354        Value *Add = Builder->CreateNUWAdd(LHS, RHS);
355        Add->takeName(&CI);
356        Constant *V[] = {
357          UndefValue::get(LHS->getType()),
358          ConstantInt::getFalse(II->getContext())
359        };
360        StructType *ST = cast<StructType>(II->getType());
361        Constant *Struct = ConstantStruct::get(ST, V);
362        return InsertValueInst::Create(Struct, Add, 0);
363      }
364    }
365  }
366  // FALL THROUGH uadd into sadd
367  case Intrinsic::sadd_with_overflow:
368    // Canonicalize constants into the RHS.
369    if (isa<Constant>(II->getArgOperand(0)) &&
370        !isa<Constant>(II->getArgOperand(1))) {
371      Value *LHS = II->getArgOperand(0);
372      II->setArgOperand(0, II->getArgOperand(1));
373      II->setArgOperand(1, LHS);
374      return II;
375    }
376
377    // X + undef -> undef
378    if (isa<UndefValue>(II->getArgOperand(1)))
379      return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
380
381    if (ConstantInt *RHS = dyn_cast<ConstantInt>(II->getArgOperand(1))) {
382      // X + 0 -> {X, false}
383      if (RHS->isZero()) {
384        Constant *V[] = {
385          UndefValue::get(II->getArgOperand(0)->getType()),
386          ConstantInt::getFalse(II->getContext())
387        };
388        Constant *Struct =
389          ConstantStruct::get(cast<StructType>(II->getType()), V);
390        return InsertValueInst::Create(Struct, II->getArgOperand(0), 0);
391      }
392    }
393    break;
394  case Intrinsic::usub_with_overflow:
395  case Intrinsic::ssub_with_overflow:
396    // undef - X -> undef
397    // X - undef -> undef
398    if (isa<UndefValue>(II->getArgOperand(0)) ||
399        isa<UndefValue>(II->getArgOperand(1)))
400      return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
401
402    if (ConstantInt *RHS = dyn_cast<ConstantInt>(II->getArgOperand(1))) {
403      // X - 0 -> {X, false}
404      if (RHS->isZero()) {
405        Constant *V[] = {
406          UndefValue::get(II->getArgOperand(0)->getType()),
407          ConstantInt::getFalse(II->getContext())
408        };
409        Constant *Struct =
410          ConstantStruct::get(cast<StructType>(II->getType()), V);
411        return InsertValueInst::Create(Struct, II->getArgOperand(0), 0);
412      }
413    }
414    break;
415  case Intrinsic::umul_with_overflow: {
416    Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
417    unsigned BitWidth = cast<IntegerType>(LHS->getType())->getBitWidth();
418
419    APInt LHSKnownZero(BitWidth, 0);
420    APInt LHSKnownOne(BitWidth, 0);
421    ComputeMaskedBits(LHS, LHSKnownZero, LHSKnownOne);
422    APInt RHSKnownZero(BitWidth, 0);
423    APInt RHSKnownOne(BitWidth, 0);
424    ComputeMaskedBits(RHS, RHSKnownZero, RHSKnownOne);
425
426    // Get the largest possible values for each operand.
427    APInt LHSMax = ~LHSKnownZero;
428    APInt RHSMax = ~RHSKnownZero;
429
430    // If multiplying the maximum values does not overflow then we can turn
431    // this into a plain NUW mul.
432    bool Overflow;
433    LHSMax.umul_ov(RHSMax, Overflow);
434    if (!Overflow) {
435      Value *Mul = Builder->CreateNUWMul(LHS, RHS, "umul_with_overflow");
436      Constant *V[] = {
437        UndefValue::get(LHS->getType()),
438        Builder->getFalse()
439      };
440      Constant *Struct = ConstantStruct::get(cast<StructType>(II->getType()),V);
441      return InsertValueInst::Create(Struct, Mul, 0);
442    }
443  } // FALL THROUGH
444  case Intrinsic::smul_with_overflow:
445    // Canonicalize constants into the RHS.
446    if (isa<Constant>(II->getArgOperand(0)) &&
447        !isa<Constant>(II->getArgOperand(1))) {
448      Value *LHS = II->getArgOperand(0);
449      II->setArgOperand(0, II->getArgOperand(1));
450      II->setArgOperand(1, LHS);
451      return II;
452    }
453
454    // X * undef -> undef
455    if (isa<UndefValue>(II->getArgOperand(1)))
456      return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
457
458    if (ConstantInt *RHSI = dyn_cast<ConstantInt>(II->getArgOperand(1))) {
459      // X*0 -> {0, false}
460      if (RHSI->isZero())
461        return ReplaceInstUsesWith(CI, Constant::getNullValue(II->getType()));
462
463      // X * 1 -> {X, false}
464      if (RHSI->equalsInt(1)) {
465        Constant *V[] = {
466          UndefValue::get(II->getArgOperand(0)->getType()),
467          ConstantInt::getFalse(II->getContext())
468        };
469        Constant *Struct =
470          ConstantStruct::get(cast<StructType>(II->getType()), V);
471        return InsertValueInst::Create(Struct, II->getArgOperand(0), 0);
472      }
473    }
474    break;
475  case Intrinsic::ppc_altivec_lvx:
476  case Intrinsic::ppc_altivec_lvxl:
477    // Turn PPC lvx -> load if the pointer is known aligned.
478    if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, TD) >= 16) {
479      Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0),
480                                         PointerType::getUnqual(II->getType()));
481      return new LoadInst(Ptr);
482    }
483    break;
484  case Intrinsic::ppc_altivec_stvx:
485  case Intrinsic::ppc_altivec_stvxl:
486    // Turn stvx -> store if the pointer is known aligned.
487    if (getOrEnforceKnownAlignment(II->getArgOperand(1), 16, TD) >= 16) {
488      Type *OpPtrTy =
489        PointerType::getUnqual(II->getArgOperand(0)->getType());
490      Value *Ptr = Builder->CreateBitCast(II->getArgOperand(1), OpPtrTy);
491      return new StoreInst(II->getArgOperand(0), Ptr);
492    }
493    break;
494  case Intrinsic::x86_sse_storeu_ps:
495  case Intrinsic::x86_sse2_storeu_pd:
496  case Intrinsic::x86_sse2_storeu_dq:
497    // Turn X86 storeu -> store if the pointer is known aligned.
498    if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, TD) >= 16) {
499      Type *OpPtrTy =
500        PointerType::getUnqual(II->getArgOperand(1)->getType());
501      Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0), OpPtrTy);
502      return new StoreInst(II->getArgOperand(1), Ptr);
503    }
504    break;
505
506  case Intrinsic::x86_sse_cvtss2si:
507  case Intrinsic::x86_sse_cvtss2si64:
508  case Intrinsic::x86_sse_cvttss2si:
509  case Intrinsic::x86_sse_cvttss2si64:
510  case Intrinsic::x86_sse2_cvtsd2si:
511  case Intrinsic::x86_sse2_cvtsd2si64:
512  case Intrinsic::x86_sse2_cvttsd2si:
513  case Intrinsic::x86_sse2_cvttsd2si64: {
514    // These intrinsics only demand the 0th element of their input vectors. If
515    // we can simplify the input based on that, do so now.
516    unsigned VWidth =
517      cast<VectorType>(II->getArgOperand(0)->getType())->getNumElements();
518    APInt DemandedElts(VWidth, 1);
519    APInt UndefElts(VWidth, 0);
520    if (Value *V = SimplifyDemandedVectorElts(II->getArgOperand(0),
521                                              DemandedElts, UndefElts)) {
522      II->setArgOperand(0, V);
523      return II;
524    }
525    break;
526  }
527
528
529  case Intrinsic::x86_sse41_pmovsxbw:
530  case Intrinsic::x86_sse41_pmovsxwd:
531  case Intrinsic::x86_sse41_pmovsxdq:
532  case Intrinsic::x86_sse41_pmovzxbw:
533  case Intrinsic::x86_sse41_pmovzxwd:
534  case Intrinsic::x86_sse41_pmovzxdq: {
535    // pmov{s|z}x ignores the upper half of their input vectors.
536    unsigned VWidth =
537      cast<VectorType>(II->getArgOperand(0)->getType())->getNumElements();
538    unsigned LowHalfElts = VWidth / 2;
539    APInt InputDemandedElts(APInt::getBitsSet(VWidth, 0, LowHalfElts));
540    APInt UndefElts(VWidth, 0);
541    if (Value *TmpV = SimplifyDemandedVectorElts(II->getArgOperand(0),
542                                                 InputDemandedElts,
543                                                 UndefElts)) {
544      II->setArgOperand(0, TmpV);
545      return II;
546    }
547    break;
548  }
549
550  case Intrinsic::ppc_altivec_vperm:
551    // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
552    if (Constant *Mask = dyn_cast<Constant>(II->getArgOperand(2))) {
553      assert(Mask->getType()->getVectorNumElements() == 16 &&
554             "Bad type for intrinsic!");
555
556      // Check that all of the elements are integer constants or undefs.
557      bool AllEltsOk = true;
558      for (unsigned i = 0; i != 16; ++i) {
559        Constant *Elt = Mask->getAggregateElement(i);
560        if (Elt == 0 ||
561            !(isa<ConstantInt>(Elt) || isa<UndefValue>(Elt))) {
562          AllEltsOk = false;
563          break;
564        }
565      }
566
567      if (AllEltsOk) {
568        // Cast the input vectors to byte vectors.
569        Value *Op0 = Builder->CreateBitCast(II->getArgOperand(0),
570                                            Mask->getType());
571        Value *Op1 = Builder->CreateBitCast(II->getArgOperand(1),
572                                            Mask->getType());
573        Value *Result = UndefValue::get(Op0->getType());
574
575        // Only extract each element once.
576        Value *ExtractedElts[32];
577        memset(ExtractedElts, 0, sizeof(ExtractedElts));
578
579        for (unsigned i = 0; i != 16; ++i) {
580          if (isa<UndefValue>(Mask->getAggregateElement(i)))
581            continue;
582          unsigned Idx =
583            cast<ConstantInt>(Mask->getAggregateElement(i))->getZExtValue();
584          Idx &= 31;  // Match the hardware behavior.
585
586          if (ExtractedElts[Idx] == 0) {
587            ExtractedElts[Idx] =
588              Builder->CreateExtractElement(Idx < 16 ? Op0 : Op1,
589                                            Builder->getInt32(Idx&15));
590          }
591
592          // Insert this value into the result vector.
593          Result = Builder->CreateInsertElement(Result, ExtractedElts[Idx],
594                                                Builder->getInt32(i));
595        }
596        return CastInst::Create(Instruction::BitCast, Result, CI.getType());
597      }
598    }
599    break;
600
601  case Intrinsic::arm_neon_vld1:
602  case Intrinsic::arm_neon_vld2:
603  case Intrinsic::arm_neon_vld3:
604  case Intrinsic::arm_neon_vld4:
605  case Intrinsic::arm_neon_vld2lane:
606  case Intrinsic::arm_neon_vld3lane:
607  case Intrinsic::arm_neon_vld4lane:
608  case Intrinsic::arm_neon_vst1:
609  case Intrinsic::arm_neon_vst2:
610  case Intrinsic::arm_neon_vst3:
611  case Intrinsic::arm_neon_vst4:
612  case Intrinsic::arm_neon_vst2lane:
613  case Intrinsic::arm_neon_vst3lane:
614  case Intrinsic::arm_neon_vst4lane: {
615    unsigned MemAlign = getKnownAlignment(II->getArgOperand(0), TD);
616    unsigned AlignArg = II->getNumArgOperands() - 1;
617    ConstantInt *IntrAlign = dyn_cast<ConstantInt>(II->getArgOperand(AlignArg));
618    if (IntrAlign && IntrAlign->getZExtValue() < MemAlign) {
619      II->setArgOperand(AlignArg,
620                        ConstantInt::get(Type::getInt32Ty(II->getContext()),
621                                         MemAlign, false));
622      return II;
623    }
624    break;
625  }
626
627  case Intrinsic::arm_neon_vmulls:
628  case Intrinsic::arm_neon_vmullu: {
629    Value *Arg0 = II->getArgOperand(0);
630    Value *Arg1 = II->getArgOperand(1);
631
632    // Handle mul by zero first:
633    if (isa<ConstantAggregateZero>(Arg0) || isa<ConstantAggregateZero>(Arg1)) {
634      return ReplaceInstUsesWith(CI, ConstantAggregateZero::get(II->getType()));
635    }
636
637    // Check for constant LHS & RHS - in this case we just simplify.
638    bool Zext = (II->getIntrinsicID() == Intrinsic::arm_neon_vmullu);
639    VectorType *NewVT = cast<VectorType>(II->getType());
640    unsigned NewWidth = NewVT->getElementType()->getIntegerBitWidth();
641    if (ConstantDataVector *CV0 = dyn_cast<ConstantDataVector>(Arg0)) {
642      if (ConstantDataVector *CV1 = dyn_cast<ConstantDataVector>(Arg1)) {
643        VectorType* VT = cast<VectorType>(CV0->getType());
644        SmallVector<Constant*, 4> NewElems;
645        for (unsigned i = 0; i < VT->getNumElements(); ++i) {
646          APInt CV0E =
647            (cast<ConstantInt>(CV0->getAggregateElement(i)))->getValue();
648          CV0E = Zext ? CV0E.zext(NewWidth) : CV0E.sext(NewWidth);
649          APInt CV1E =
650            (cast<ConstantInt>(CV1->getAggregateElement(i)))->getValue();
651          CV1E = Zext ? CV1E.zext(NewWidth) : CV1E.sext(NewWidth);
652          NewElems.push_back(
653            ConstantInt::get(NewVT->getElementType(), CV0E * CV1E));
654        }
655        return ReplaceInstUsesWith(CI, ConstantVector::get(NewElems));
656      }
657
658      // Couldn't simplify - cannonicalize constant to the RHS.
659      std::swap(Arg0, Arg1);
660    }
661
662    // Handle mul by one:
663    if (ConstantDataVector *CV1 = dyn_cast<ConstantDataVector>(Arg1)) {
664      if (ConstantInt *Splat =
665            dyn_cast_or_null<ConstantInt>(CV1->getSplatValue())) {
666        if (Splat->isOne()) {
667          if (Zext)
668            return CastInst::CreateZExtOrBitCast(Arg0, II->getType());
669          // else
670          return CastInst::CreateSExtOrBitCast(Arg0, II->getType());
671        }
672      }
673    }
674
675    break;
676  }
677
678  case Intrinsic::stackrestore: {
679    // If the save is right next to the restore, remove the restore.  This can
680    // happen when variable allocas are DCE'd.
681    if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getArgOperand(0))) {
682      if (SS->getIntrinsicID() == Intrinsic::stacksave) {
683        BasicBlock::iterator BI = SS;
684        if (&*++BI == II)
685          return EraseInstFromFunction(CI);
686      }
687    }
688
689    // Scan down this block to see if there is another stack restore in the
690    // same block without an intervening call/alloca.
691    BasicBlock::iterator BI = II;
692    TerminatorInst *TI = II->getParent()->getTerminator();
693    bool CannotRemove = false;
694    for (++BI; &*BI != TI; ++BI) {
695      if (isa<AllocaInst>(BI)) {
696        CannotRemove = true;
697        break;
698      }
699      if (CallInst *BCI = dyn_cast<CallInst>(BI)) {
700        if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BCI)) {
701          // If there is a stackrestore below this one, remove this one.
702          if (II->getIntrinsicID() == Intrinsic::stackrestore)
703            return EraseInstFromFunction(CI);
704          // Otherwise, ignore the intrinsic.
705        } else {
706          // If we found a non-intrinsic call, we can't remove the stack
707          // restore.
708          CannotRemove = true;
709          break;
710        }
711      }
712    }
713
714    // If the stack restore is in a return, resume, or unwind block and if there
715    // are no allocas or calls between the restore and the return, nuke the
716    // restore.
717    if (!CannotRemove && (isa<ReturnInst>(TI) || isa<ResumeInst>(TI)))
718      return EraseInstFromFunction(CI);
719    break;
720  }
721  }
722
723  return visitCallSite(II);
724}
725
726// InvokeInst simplification
727//
728Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
729  return visitCallSite(&II);
730}
731
732/// isSafeToEliminateVarargsCast - If this cast does not affect the value
733/// passed through the varargs area, we can eliminate the use of the cast.
734static bool isSafeToEliminateVarargsCast(const CallSite CS,
735                                         const CastInst * const CI,
736                                         const TargetData * const TD,
737                                         const int ix) {
738  if (!CI->isLosslessCast())
739    return false;
740
741  // The size of ByVal arguments is derived from the type, so we
742  // can't change to a type with a different size.  If the size were
743  // passed explicitly we could avoid this check.
744  if (!CS.isByValArgument(ix))
745    return true;
746
747  Type* SrcTy =
748            cast<PointerType>(CI->getOperand(0)->getType())->getElementType();
749  Type* DstTy = cast<PointerType>(CI->getType())->getElementType();
750  if (!SrcTy->isSized() || !DstTy->isSized())
751    return false;
752  if (!TD || TD->getTypeAllocSize(SrcTy) != TD->getTypeAllocSize(DstTy))
753    return false;
754  return true;
755}
756
757namespace {
758class InstCombineFortifiedLibCalls : public SimplifyFortifiedLibCalls {
759  InstCombiner *IC;
760protected:
761  void replaceCall(Value *With) {
762    NewInstruction = IC->ReplaceInstUsesWith(*CI, With);
763  }
764  bool isFoldable(unsigned SizeCIOp, unsigned SizeArgOp, bool isString) const {
765    if (CI->getArgOperand(SizeCIOp) == CI->getArgOperand(SizeArgOp))
766      return true;
767    if (ConstantInt *SizeCI =
768                           dyn_cast<ConstantInt>(CI->getArgOperand(SizeCIOp))) {
769      if (SizeCI->isAllOnesValue())
770        return true;
771      if (isString) {
772        uint64_t Len = GetStringLength(CI->getArgOperand(SizeArgOp));
773        // If the length is 0 we don't know how long it is and so we can't
774        // remove the check.
775        if (Len == 0) return false;
776        return SizeCI->getZExtValue() >= Len;
777      }
778      if (ConstantInt *Arg = dyn_cast<ConstantInt>(
779                                                  CI->getArgOperand(SizeArgOp)))
780        return SizeCI->getZExtValue() >= Arg->getZExtValue();
781    }
782    return false;
783  }
784public:
785  InstCombineFortifiedLibCalls(InstCombiner *IC) : IC(IC), NewInstruction(0) { }
786  Instruction *NewInstruction;
787};
788} // end anonymous namespace
789
790// Try to fold some different type of calls here.
791// Currently we're only working with the checking functions, memcpy_chk,
792// mempcpy_chk, memmove_chk, memset_chk, strcpy_chk, stpcpy_chk, strncpy_chk,
793// strcat_chk and strncat_chk.
794Instruction *InstCombiner::tryOptimizeCall(CallInst *CI, const TargetData *TD) {
795  if (CI->getCalledFunction() == 0) return 0;
796
797  InstCombineFortifiedLibCalls Simplifier(this);
798  Simplifier.fold(CI, TD);
799  return Simplifier.NewInstruction;
800}
801
802static IntrinsicInst *FindInitTrampolineFromAlloca(Value *TrampMem) {
803  // Strip off at most one level of pointer casts, looking for an alloca.  This
804  // is good enough in practice and simpler than handling any number of casts.
805  Value *Underlying = TrampMem->stripPointerCasts();
806  if (Underlying != TrampMem &&
807      (!Underlying->hasOneUse() || *Underlying->use_begin() != TrampMem))
808    return 0;
809  if (!isa<AllocaInst>(Underlying))
810    return 0;
811
812  IntrinsicInst *InitTrampoline = 0;
813  for (Value::use_iterator I = TrampMem->use_begin(), E = TrampMem->use_end();
814       I != E; I++) {
815    IntrinsicInst *II = dyn_cast<IntrinsicInst>(*I);
816    if (!II)
817      return 0;
818    if (II->getIntrinsicID() == Intrinsic::init_trampoline) {
819      if (InitTrampoline)
820        // More than one init_trampoline writes to this value.  Give up.
821        return 0;
822      InitTrampoline = II;
823      continue;
824    }
825    if (II->getIntrinsicID() == Intrinsic::adjust_trampoline)
826      // Allow any number of calls to adjust.trampoline.
827      continue;
828    return 0;
829  }
830
831  // No call to init.trampoline found.
832  if (!InitTrampoline)
833    return 0;
834
835  // Check that the alloca is being used in the expected way.
836  if (InitTrampoline->getOperand(0) != TrampMem)
837    return 0;
838
839  return InitTrampoline;
840}
841
842static IntrinsicInst *FindInitTrampolineFromBB(IntrinsicInst *AdjustTramp,
843                                               Value *TrampMem) {
844  // Visit all the previous instructions in the basic block, and try to find a
845  // init.trampoline which has a direct path to the adjust.trampoline.
846  for (BasicBlock::iterator I = AdjustTramp,
847       E = AdjustTramp->getParent()->begin(); I != E; ) {
848    Instruction *Inst = --I;
849    if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
850      if (II->getIntrinsicID() == Intrinsic::init_trampoline &&
851          II->getOperand(0) == TrampMem)
852        return II;
853    if (Inst->mayWriteToMemory())
854      return 0;
855  }
856  return 0;
857}
858
859// Given a call to llvm.adjust.trampoline, find and return the corresponding
860// call to llvm.init.trampoline if the call to the trampoline can be optimized
861// to a direct call to a function.  Otherwise return NULL.
862//
863static IntrinsicInst *FindInitTrampoline(Value *Callee) {
864  Callee = Callee->stripPointerCasts();
865  IntrinsicInst *AdjustTramp = dyn_cast<IntrinsicInst>(Callee);
866  if (!AdjustTramp ||
867      AdjustTramp->getIntrinsicID() != Intrinsic::adjust_trampoline)
868    return 0;
869
870  Value *TrampMem = AdjustTramp->getOperand(0);
871
872  if (IntrinsicInst *IT = FindInitTrampolineFromAlloca(TrampMem))
873    return IT;
874  if (IntrinsicInst *IT = FindInitTrampolineFromBB(AdjustTramp, TrampMem))
875    return IT;
876  return 0;
877}
878
879// visitCallSite - Improvements for call and invoke instructions.
880//
881Instruction *InstCombiner::visitCallSite(CallSite CS) {
882  if (isAllocLikeFn(CS.getInstruction()))
883    return visitAllocSite(*CS.getInstruction());
884
885  bool Changed = false;
886
887  // If the callee is a pointer to a function, attempt to move any casts to the
888  // arguments of the call/invoke.
889  Value *Callee = CS.getCalledValue();
890  if (!isa<Function>(Callee) && transformConstExprCastCall(CS))
891    return 0;
892
893  if (Function *CalleeF = dyn_cast<Function>(Callee))
894    // If the call and callee calling conventions don't match, this call must
895    // be unreachable, as the call is undefined.
896    if (CalleeF->getCallingConv() != CS.getCallingConv() &&
897        // Only do this for calls to a function with a body.  A prototype may
898        // not actually end up matching the implementation's calling conv for a
899        // variety of reasons (e.g. it may be written in assembly).
900        !CalleeF->isDeclaration()) {
901      Instruction *OldCall = CS.getInstruction();
902      new StoreInst(ConstantInt::getTrue(Callee->getContext()),
903                UndefValue::get(Type::getInt1PtrTy(Callee->getContext())),
904                                  OldCall);
905      // If OldCall dues not return void then replaceAllUsesWith undef.
906      // This allows ValueHandlers and custom metadata to adjust itself.
907      if (!OldCall->getType()->isVoidTy())
908        ReplaceInstUsesWith(*OldCall, UndefValue::get(OldCall->getType()));
909      if (isa<CallInst>(OldCall))
910        return EraseInstFromFunction(*OldCall);
911
912      // We cannot remove an invoke, because it would change the CFG, just
913      // change the callee to a null pointer.
914      cast<InvokeInst>(OldCall)->setCalledFunction(
915                                    Constant::getNullValue(CalleeF->getType()));
916      return 0;
917    }
918
919  if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
920    // If CS does not return void then replaceAllUsesWith undef.
921    // This allows ValueHandlers and custom metadata to adjust itself.
922    if (!CS.getInstruction()->getType()->isVoidTy())
923      ReplaceInstUsesWith(*CS.getInstruction(),
924                          UndefValue::get(CS.getInstruction()->getType()));
925
926    if (isa<InvokeInst>(CS.getInstruction())) {
927      // Can't remove an invoke because we cannot change the CFG.
928      return 0;
929    }
930
931    // This instruction is not reachable, just remove it.  We insert a store to
932    // undef so that we know that this code is not reachable, despite the fact
933    // that we can't modify the CFG here.
934    new StoreInst(ConstantInt::getTrue(Callee->getContext()),
935                  UndefValue::get(Type::getInt1PtrTy(Callee->getContext())),
936                  CS.getInstruction());
937
938    return EraseInstFromFunction(*CS.getInstruction());
939  }
940
941  if (IntrinsicInst *II = FindInitTrampoline(Callee))
942    return transformCallThroughTrampoline(CS, II);
943
944  PointerType *PTy = cast<PointerType>(Callee->getType());
945  FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
946  if (FTy->isVarArg()) {
947    int ix = FTy->getNumParams();
948    // See if we can optimize any arguments passed through the varargs area of
949    // the call.
950    for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
951           E = CS.arg_end(); I != E; ++I, ++ix) {
952      CastInst *CI = dyn_cast<CastInst>(*I);
953      if (CI && isSafeToEliminateVarargsCast(CS, CI, TD, ix)) {
954        *I = CI->getOperand(0);
955        Changed = true;
956      }
957    }
958  }
959
960  if (isa<InlineAsm>(Callee) && !CS.doesNotThrow()) {
961    // Inline asm calls cannot throw - mark them 'nounwind'.
962    CS.setDoesNotThrow();
963    Changed = true;
964  }
965
966  // Try to optimize the call if possible, we require TargetData for most of
967  // this.  None of these calls are seen as possibly dead so go ahead and
968  // delete the instruction now.
969  if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction())) {
970    Instruction *I = tryOptimizeCall(CI, TD);
971    // If we changed something return the result, etc. Otherwise let
972    // the fallthrough check.
973    if (I) return EraseInstFromFunction(*I);
974  }
975
976  return Changed ? CS.getInstruction() : 0;
977}
978
979// transformConstExprCastCall - If the callee is a constexpr cast of a function,
980// attempt to move the cast to the arguments of the call/invoke.
981//
982bool InstCombiner::transformConstExprCastCall(CallSite CS) {
983  Function *Callee =
984    dyn_cast<Function>(CS.getCalledValue()->stripPointerCasts());
985  if (Callee == 0)
986    return false;
987  Instruction *Caller = CS.getInstruction();
988  const AttrListPtr &CallerPAL = CS.getAttributes();
989
990  // Okay, this is a cast from a function to a different type.  Unless doing so
991  // would cause a type conversion of one of our arguments, change this call to
992  // be a direct call with arguments casted to the appropriate types.
993  //
994  FunctionType *FT = Callee->getFunctionType();
995  Type *OldRetTy = Caller->getType();
996  Type *NewRetTy = FT->getReturnType();
997
998  if (NewRetTy->isStructTy())
999    return false; // TODO: Handle multiple return values.
1000
1001  // Check to see if we are changing the return type...
1002  if (OldRetTy != NewRetTy) {
1003    if (Callee->isDeclaration() &&
1004        // Conversion is ok if changing from one pointer type to another or from
1005        // a pointer to an integer of the same size.
1006        !((OldRetTy->isPointerTy() || !TD ||
1007           OldRetTy == TD->getIntPtrType(Caller->getContext())) &&
1008          (NewRetTy->isPointerTy() || !TD ||
1009           NewRetTy == TD->getIntPtrType(Caller->getContext()))))
1010      return false;   // Cannot transform this return value.
1011
1012    if (!Caller->use_empty() &&
1013        // void -> non-void is handled specially
1014        !NewRetTy->isVoidTy() && !CastInst::isCastable(NewRetTy, OldRetTy))
1015      return false;   // Cannot transform this return value.
1016
1017    if (!CallerPAL.isEmpty() && !Caller->use_empty()) {
1018      Attributes RAttrs = CallerPAL.getRetAttributes();
1019      if (RAttrs & Attribute::typeIncompatible(NewRetTy))
1020        return false;   // Attribute not compatible with transformed value.
1021    }
1022
1023    // If the callsite is an invoke instruction, and the return value is used by
1024    // a PHI node in a successor, we cannot change the return type of the call
1025    // because there is no place to put the cast instruction (without breaking
1026    // the critical edge).  Bail out in this case.
1027    if (!Caller->use_empty())
1028      if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
1029        for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
1030             UI != E; ++UI)
1031          if (PHINode *PN = dyn_cast<PHINode>(*UI))
1032            if (PN->getParent() == II->getNormalDest() ||
1033                PN->getParent() == II->getUnwindDest())
1034              return false;
1035  }
1036
1037  unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
1038  unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
1039
1040  CallSite::arg_iterator AI = CS.arg_begin();
1041  for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
1042    Type *ParamTy = FT->getParamType(i);
1043    Type *ActTy = (*AI)->getType();
1044
1045    if (!CastInst::isCastable(ActTy, ParamTy))
1046      return false;   // Cannot transform this parameter value.
1047
1048    Attributes Attrs = CallerPAL.getParamAttributes(i + 1);
1049    if (Attrs & Attribute::typeIncompatible(ParamTy))
1050      return false;   // Attribute not compatible with transformed value.
1051
1052    // If the parameter is passed as a byval argument, then we have to have a
1053    // sized type and the sized type has to have the same size as the old type.
1054    if (ParamTy != ActTy && (Attrs & Attribute::ByVal)) {
1055      PointerType *ParamPTy = dyn_cast<PointerType>(ParamTy);
1056      if (ParamPTy == 0 || !ParamPTy->getElementType()->isSized() || TD == 0)
1057        return false;
1058
1059      Type *CurElTy = cast<PointerType>(ActTy)->getElementType();
1060      if (TD->getTypeAllocSize(CurElTy) !=
1061          TD->getTypeAllocSize(ParamPTy->getElementType()))
1062        return false;
1063    }
1064
1065    // Converting from one pointer type to another or between a pointer and an
1066    // integer of the same size is safe even if we do not have a body.
1067    bool isConvertible = ActTy == ParamTy ||
1068      (TD && ((ParamTy->isPointerTy() ||
1069      ParamTy == TD->getIntPtrType(Caller->getContext())) &&
1070              (ActTy->isPointerTy() ||
1071              ActTy == TD->getIntPtrType(Caller->getContext()))));
1072    if (Callee->isDeclaration() && !isConvertible) return false;
1073  }
1074
1075  if (Callee->isDeclaration()) {
1076    // Do not delete arguments unless we have a function body.
1077    if (FT->getNumParams() < NumActualArgs && !FT->isVarArg())
1078      return false;
1079
1080    // If the callee is just a declaration, don't change the varargsness of the
1081    // call.  We don't want to introduce a varargs call where one doesn't
1082    // already exist.
1083    PointerType *APTy = cast<PointerType>(CS.getCalledValue()->getType());
1084    if (FT->isVarArg()!=cast<FunctionType>(APTy->getElementType())->isVarArg())
1085      return false;
1086
1087    // If both the callee and the cast type are varargs, we still have to make
1088    // sure the number of fixed parameters are the same or we have the same
1089    // ABI issues as if we introduce a varargs call.
1090    if (FT->isVarArg() &&
1091        cast<FunctionType>(APTy->getElementType())->isVarArg() &&
1092        FT->getNumParams() !=
1093        cast<FunctionType>(APTy->getElementType())->getNumParams())
1094      return false;
1095  }
1096
1097  if (FT->getNumParams() < NumActualArgs && FT->isVarArg() &&
1098      !CallerPAL.isEmpty())
1099    // In this case we have more arguments than the new function type, but we
1100    // won't be dropping them.  Check that these extra arguments have attributes
1101    // that are compatible with being a vararg call argument.
1102    for (unsigned i = CallerPAL.getNumSlots(); i; --i) {
1103      if (CallerPAL.getSlot(i - 1).Index <= FT->getNumParams())
1104        break;
1105      Attributes PAttrs = CallerPAL.getSlot(i - 1).Attrs;
1106      if (PAttrs & Attribute::VarArgsIncompatible)
1107        return false;
1108    }
1109
1110
1111  // Okay, we decided that this is a safe thing to do: go ahead and start
1112  // inserting cast instructions as necessary.
1113  std::vector<Value*> Args;
1114  Args.reserve(NumActualArgs);
1115  SmallVector<AttributeWithIndex, 8> attrVec;
1116  attrVec.reserve(NumCommonArgs);
1117
1118  // Get any return attributes.
1119  Attributes RAttrs = CallerPAL.getRetAttributes();
1120
1121  // If the return value is not being used, the type may not be compatible
1122  // with the existing attributes.  Wipe out any problematic attributes.
1123  RAttrs &= ~Attribute::typeIncompatible(NewRetTy);
1124
1125  // Add the new return attributes.
1126  if (RAttrs)
1127    attrVec.push_back(AttributeWithIndex::get(0, RAttrs));
1128
1129  AI = CS.arg_begin();
1130  for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
1131    Type *ParamTy = FT->getParamType(i);
1132    if ((*AI)->getType() == ParamTy) {
1133      Args.push_back(*AI);
1134    } else {
1135      Instruction::CastOps opcode = CastInst::getCastOpcode(*AI,
1136          false, ParamTy, false);
1137      Args.push_back(Builder->CreateCast(opcode, *AI, ParamTy));
1138    }
1139
1140    // Add any parameter attributes.
1141    if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1))
1142      attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
1143  }
1144
1145  // If the function takes more arguments than the call was taking, add them
1146  // now.
1147  for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
1148    Args.push_back(Constant::getNullValue(FT->getParamType(i)));
1149
1150  // If we are removing arguments to the function, emit an obnoxious warning.
1151  if (FT->getNumParams() < NumActualArgs) {
1152    if (!FT->isVarArg()) {
1153      errs() << "WARNING: While resolving call to function '"
1154             << Callee->getName() << "' arguments were dropped!\n";
1155    } else {
1156      // Add all of the arguments in their promoted form to the arg list.
1157      for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
1158        Type *PTy = getPromotedType((*AI)->getType());
1159        if (PTy != (*AI)->getType()) {
1160          // Must promote to pass through va_arg area!
1161          Instruction::CastOps opcode =
1162            CastInst::getCastOpcode(*AI, false, PTy, false);
1163          Args.push_back(Builder->CreateCast(opcode, *AI, PTy));
1164        } else {
1165          Args.push_back(*AI);
1166        }
1167
1168        // Add any parameter attributes.
1169        if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1))
1170          attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
1171      }
1172    }
1173  }
1174
1175  if (Attributes FnAttrs =  CallerPAL.getFnAttributes())
1176    attrVec.push_back(AttributeWithIndex::get(~0, FnAttrs));
1177
1178  if (NewRetTy->isVoidTy())
1179    Caller->setName("");   // Void type should not have a name.
1180
1181  const AttrListPtr &NewCallerPAL = AttrListPtr::get(attrVec);
1182
1183  Instruction *NC;
1184  if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
1185    NC = Builder->CreateInvoke(Callee, II->getNormalDest(),
1186                               II->getUnwindDest(), Args);
1187    NC->takeName(II);
1188    cast<InvokeInst>(NC)->setCallingConv(II->getCallingConv());
1189    cast<InvokeInst>(NC)->setAttributes(NewCallerPAL);
1190  } else {
1191    CallInst *CI = cast<CallInst>(Caller);
1192    NC = Builder->CreateCall(Callee, Args);
1193    NC->takeName(CI);
1194    if (CI->isTailCall())
1195      cast<CallInst>(NC)->setTailCall();
1196    cast<CallInst>(NC)->setCallingConv(CI->getCallingConv());
1197    cast<CallInst>(NC)->setAttributes(NewCallerPAL);
1198  }
1199
1200  // Insert a cast of the return type as necessary.
1201  Value *NV = NC;
1202  if (OldRetTy != NV->getType() && !Caller->use_empty()) {
1203    if (!NV->getType()->isVoidTy()) {
1204      Instruction::CastOps opcode =
1205        CastInst::getCastOpcode(NC, false, OldRetTy, false);
1206      NV = NC = CastInst::Create(opcode, NC, OldRetTy);
1207      NC->setDebugLoc(Caller->getDebugLoc());
1208
1209      // If this is an invoke instruction, we should insert it after the first
1210      // non-phi, instruction in the normal successor block.
1211      if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
1212        BasicBlock::iterator I = II->getNormalDest()->getFirstInsertionPt();
1213        InsertNewInstBefore(NC, *I);
1214      } else {
1215        // Otherwise, it's a call, just insert cast right after the call.
1216        InsertNewInstBefore(NC, *Caller);
1217      }
1218      Worklist.AddUsersToWorkList(*Caller);
1219    } else {
1220      NV = UndefValue::get(Caller->getType());
1221    }
1222  }
1223
1224  if (!Caller->use_empty())
1225    ReplaceInstUsesWith(*Caller, NV);
1226
1227  EraseInstFromFunction(*Caller);
1228  return true;
1229}
1230
1231// transformCallThroughTrampoline - Turn a call to a function created by
1232// init_trampoline / adjust_trampoline intrinsic pair into a direct call to the
1233// underlying function.
1234//
1235Instruction *
1236InstCombiner::transformCallThroughTrampoline(CallSite CS,
1237                                             IntrinsicInst *Tramp) {
1238  Value *Callee = CS.getCalledValue();
1239  PointerType *PTy = cast<PointerType>(Callee->getType());
1240  FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1241  const AttrListPtr &Attrs = CS.getAttributes();
1242
1243  // If the call already has the 'nest' attribute somewhere then give up -
1244  // otherwise 'nest' would occur twice after splicing in the chain.
1245  if (Attrs.hasAttrSomewhere(Attribute::Nest))
1246    return 0;
1247
1248  assert(Tramp &&
1249         "transformCallThroughTrampoline called with incorrect CallSite.");
1250
1251  Function *NestF =cast<Function>(Tramp->getArgOperand(1)->stripPointerCasts());
1252  PointerType *NestFPTy = cast<PointerType>(NestF->getType());
1253  FunctionType *NestFTy = cast<FunctionType>(NestFPTy->getElementType());
1254
1255  const AttrListPtr &NestAttrs = NestF->getAttributes();
1256  if (!NestAttrs.isEmpty()) {
1257    unsigned NestIdx = 1;
1258    Type *NestTy = 0;
1259    Attributes NestAttr = Attribute::None;
1260
1261    // Look for a parameter marked with the 'nest' attribute.
1262    for (FunctionType::param_iterator I = NestFTy->param_begin(),
1263         E = NestFTy->param_end(); I != E; ++NestIdx, ++I)
1264      if (NestAttrs.paramHasAttr(NestIdx, Attribute::Nest)) {
1265        // Record the parameter type and any other attributes.
1266        NestTy = *I;
1267        NestAttr = NestAttrs.getParamAttributes(NestIdx);
1268        break;
1269      }
1270
1271    if (NestTy) {
1272      Instruction *Caller = CS.getInstruction();
1273      std::vector<Value*> NewArgs;
1274      NewArgs.reserve(unsigned(CS.arg_end()-CS.arg_begin())+1);
1275
1276      SmallVector<AttributeWithIndex, 8> NewAttrs;
1277      NewAttrs.reserve(Attrs.getNumSlots() + 1);
1278
1279      // Insert the nest argument into the call argument list, which may
1280      // mean appending it.  Likewise for attributes.
1281
1282      // Add any result attributes.
1283      if (Attributes Attr = Attrs.getRetAttributes())
1284        NewAttrs.push_back(AttributeWithIndex::get(0, Attr));
1285
1286      {
1287        unsigned Idx = 1;
1288        CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
1289        do {
1290          if (Idx == NestIdx) {
1291            // Add the chain argument and attributes.
1292            Value *NestVal = Tramp->getArgOperand(2);
1293            if (NestVal->getType() != NestTy)
1294              NestVal = Builder->CreateBitCast(NestVal, NestTy, "nest");
1295            NewArgs.push_back(NestVal);
1296            NewAttrs.push_back(AttributeWithIndex::get(NestIdx, NestAttr));
1297          }
1298
1299          if (I == E)
1300            break;
1301
1302          // Add the original argument and attributes.
1303          NewArgs.push_back(*I);
1304          if (Attributes Attr = Attrs.getParamAttributes(Idx))
1305            NewAttrs.push_back
1306              (AttributeWithIndex::get(Idx + (Idx >= NestIdx), Attr));
1307
1308          ++Idx, ++I;
1309        } while (1);
1310      }
1311
1312      // Add any function attributes.
1313      if (Attributes Attr = Attrs.getFnAttributes())
1314        NewAttrs.push_back(AttributeWithIndex::get(~0, Attr));
1315
1316      // The trampoline may have been bitcast to a bogus type (FTy).
1317      // Handle this by synthesizing a new function type, equal to FTy
1318      // with the chain parameter inserted.
1319
1320      std::vector<Type*> NewTypes;
1321      NewTypes.reserve(FTy->getNumParams()+1);
1322
1323      // Insert the chain's type into the list of parameter types, which may
1324      // mean appending it.
1325      {
1326        unsigned Idx = 1;
1327        FunctionType::param_iterator I = FTy->param_begin(),
1328          E = FTy->param_end();
1329
1330        do {
1331          if (Idx == NestIdx)
1332            // Add the chain's type.
1333            NewTypes.push_back(NestTy);
1334
1335          if (I == E)
1336            break;
1337
1338          // Add the original type.
1339          NewTypes.push_back(*I);
1340
1341          ++Idx, ++I;
1342        } while (1);
1343      }
1344
1345      // Replace the trampoline call with a direct call.  Let the generic
1346      // code sort out any function type mismatches.
1347      FunctionType *NewFTy = FunctionType::get(FTy->getReturnType(), NewTypes,
1348                                                FTy->isVarArg());
1349      Constant *NewCallee =
1350        NestF->getType() == PointerType::getUnqual(NewFTy) ?
1351        NestF : ConstantExpr::getBitCast(NestF,
1352                                         PointerType::getUnqual(NewFTy));
1353      const AttrListPtr &NewPAL = AttrListPtr::get(NewAttrs);
1354
1355      Instruction *NewCaller;
1356      if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
1357        NewCaller = InvokeInst::Create(NewCallee,
1358                                       II->getNormalDest(), II->getUnwindDest(),
1359                                       NewArgs);
1360        cast<InvokeInst>(NewCaller)->setCallingConv(II->getCallingConv());
1361        cast<InvokeInst>(NewCaller)->setAttributes(NewPAL);
1362      } else {
1363        NewCaller = CallInst::Create(NewCallee, NewArgs);
1364        if (cast<CallInst>(Caller)->isTailCall())
1365          cast<CallInst>(NewCaller)->setTailCall();
1366        cast<CallInst>(NewCaller)->
1367          setCallingConv(cast<CallInst>(Caller)->getCallingConv());
1368        cast<CallInst>(NewCaller)->setAttributes(NewPAL);
1369      }
1370
1371      return NewCaller;
1372    }
1373  }
1374
1375  // Replace the trampoline call with a direct call.  Since there is no 'nest'
1376  // parameter, there is no need to adjust the argument list.  Let the generic
1377  // code sort out any function type mismatches.
1378  Constant *NewCallee =
1379    NestF->getType() == PTy ? NestF :
1380                              ConstantExpr::getBitCast(NestF, PTy);
1381  CS.setCalledFunction(NewCallee);
1382  return CS.getInstruction();
1383}
1384